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Curtain Lining Calculator — Lining & Interlining
Work out lining fabric and interlining requirements for professional curtains.
Adds body, insulation and luxury drape
How We Calculate This
Lining uses the same number of fabric widths as the face fabric, so this calculator carries your Total Fabric Widths straight across. The lining cut drop is the finished curtain drop plus a hem allowance only — there is no heading allowance, because the lining is fixed below the heading tape rather than turned over the top (sew-helpful workroom method).
The formula
Lining drop = Finished drop + 16cm hem (12cm for sill-length) + 0cm heading
Lining widths = Same as face fabric widths
Lining fabric (m) = Widths × Lining drop ÷ 100
Standard cotton sateen lining is 137cm (54 inch) wide. Interlining (bump or domette) uses the same widths and is cut to the finished drop plus a small allowance.
Frequently Asked Questions
Lining uses the same number of fabric widths as the face fabric, so this calculator carries your Total Fabric Widths straight across. Standard cotton sateen lining is 137cm wide (54 inch), close to most curtain fabric, and is trimmed 2-4cm narrower on each side so it does not show from the front.
Lining is cut slightly shorter than the face fabric so it sits above the curtain hem. The standard workroom allowance is a 16cm hem for floor-length curtains (12cm for sill-length), with no heading allowance because the lining is fixed below the heading tape rather than turned over the top.
Interlining (bump or domette) sits between the face fabric and lining. It adds body, improves drape, provides insulation, and blocks more light. Use it for professional or luxurious curtains, especially in living rooms and bedrooms.
Standard cotton sateen lining is most common. Blackout lining blocks light for bedrooms. Thermal lining adds insulation. For south-facing windows, consider fade-resistant lining to protect the face fabric.
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Last updated: February 2026
All calculations are estimates. Always verify quantities before cutting or purchasing fabric.